96份桑树地方品种农艺性状的关联分析 英文标题:Association Analysis of Agronomic Traits in 96 Mulberry Local Collections
收藏资源简介：
我国是世界蚕业的发源地，也是桑树的重要起源中心之一。桑树是多年生的重要经济作物，也家蚕的唯一饲料。桑树品种，桑叶产量及叶质是养蚕的决定性因素。不断提高桑树品种的产量、品质、抗病性和适应性是现代桑树育种家追求的主要目标。本研究在桑树表型研究的基础上，对我国桑树地方品种的性状进行关联分析，从而寻找与其表型相关的优异基因，从分子水平解释桑树表型性状的遗传变异规律，进而为桑树数量性状遗传改良研究提供理论基础，为桑树杂交育种寻求新途径。本文通过对对黄河流域鲁桑、太湖流域湖桑两种生态类型共96份桑树地方品种的21个农艺性状进行分析研究，利用ISSR标记的多态性对供试材料进行遗传多样性和群体结构分析，并分析遗传标记与表型性状的相关性。主要研究内容如下:1.本次试验通过对96份桑树地方种质资源21个农艺性状的调查，利用SPSS软件对田间所调查到数据进行处理和分析。结果表明，96份不同桑树地方品种的21个农艺性状之间的变异幅度存在较大差异，其中变异系数都在30%以上的性状为生长芽率、春米条叶、秋公斤数、梢梗叶、椹梗比、叶梗比和株产叶量，梢梗比、椹梗比和叶梗比的变异系数甚至达到了50%以上，椹梗比的变异系数最大为180.99%，秋万头茧量的变异系数最小为9.32%。这一结果表明供试桑树种质资源品种间的各性状存在较大差异和多样性，可为桑树育种提供丰富的亲本材料。通过对各农艺性状之间的相关性分析可知，春担桑茧量与各性状之间的相关性不显著，其余的20个农艺性状都存在着一定的相关性，分析结果表明影响桑树产量和品质的21个农艺性状之间并不是单独孤立的，而是相互关联的，正是这些农艺性状之间通过相互协调、相互制约从而控制桑树的品质和产量。2.利用ISSR分子标记对96份桑树种质资源进行遗传多样性和群体结构分析，10对ISSR引物共扩增出93条清晰的带，其中73条带具有多态性，多态性条带百分率为78.49%。不同引物的扩增带数从7~11不等，平均每个引物扩增的条带数为9.3条，平均每个引物扩增的多态性条带数为7.3条。遗传多样性分析结果显示平均每个位点观测等位基因数为1.7957，有效等位基因数为1.4964，Nei’s遗传多样性指数为0.2869，Shannon’s信息指数为0.4268。表明96份供试材料之间的ISSR变异大，多态性高。基于遗传系数的UPGMA聚类分析结果与基于贝叶斯数学模型的群体结构聚类分析结果完全一致，均将96份供试桑树种质地方品种分为两大类。3.通过TASSEL2.1软件的MLM模型，把Structure软件计算出的群体结构数据(Q值)作为协变量，将96份供试材料的亲缘关系K矩阵连同叶长、叶幅、节间距等农艺性状表型数据对93个多态性标记位点进行标记和性状间的关联分析。分析结果显示参试的10个ISSR标记共93个多态性位点中，在P<0.01的极显著情况下，与叶长、节间距等15个农艺性状相关的标记位点共有28个，变异解释率为5.42%~16.35%。其中与叶长相关的位点有2个，与节间距、生长芽率和秋万头茧量相关联的位点各有3个，与春米条叶、春万头茧量、春担桑茧量相关联的位点各有5个，有2个标记位点与秋米条叶相关联，春公斤数、条梗叶和株产叶量都有4个标记位点与之相关联，秋公斤数只与1个位点相关联，叶梗比与6个标记位点相关联，与梢梗比和春万茧层量相关联的标记位点各有7个。在28个标记位点中有1个标记位点同时与5个农艺性状相关联，有4个位点同时与4个农艺性状相关联，有4个标记位点同时与3个农艺性状相关联，有10个位点同时与2个农艺性状相关联。叶幅、发芽率等6个农艺性状未检测出与其相关联的标记位点。研究结果对桑树种质资源重要农艺性状基因的发掘和利用以及遗传育种都具有一定的指导意义。
China is the birthplace of global sericulture and one of the important origin centers of mulberry. As an important perennial cash crop, mulberry is also the sole feed for silkworms. Mulberry varieties, mulberry leaf yield and leaf quality are the decisive factors for sericulture. Continuously improving the yield, quality, disease resistance and adaptability of mulberry varieties is the primary goal pursued by modern mulberry breeders. Based on mulberry phenotypic research, this study conducted association analysis on traits of Chinese mulberry landraces, to identify elite genes associated with their phenotypes, explain the genetic variation rules of mulberry phenotypic traits at the molecular level, thereby providing a theoretical basis for studies on genetic improvement of quantitative traits in mulberry, and seeking new approaches for mulberry crossbreeding. By analyzing 21 agronomic traits of 96 mulberry landraces from two ecological types (Morus multicaulis Perr. in the Yellow River Basin and Husang in the Taihu Lake Basin), this study conducted genetic diversity and population structure analysis on the test materials using the polymorphism of ISSR markers, and analyzed the correlation between genetic markers and phenotypic traits. The main research contents are as follows: 1. In this experiment, 21 agronomic traits of 96 mulberry landrace germplasm resources were investigated, and the field survey data were processed and analyzed using SPSS software. The results showed that there were significant differences in the variation ranges of the 21 agronomic traits among the 96 mulberry landraces. The traits with a coefficient of variation (CV) above 30% included shoot germination rate, spring per-meter branch leaf yield, autumn leaf weight per unit, shoot-stem leaf ratio, fruit-stem ratio, leaf-stem ratio and per-plant leaf yield. The CVs of shoot-stem leaf ratio, fruit-stem ratio and leaf-stem ratio even exceeded 50%, with the maximum CV of 180.99% for fruit-stem ratio and the minimum CV of 9.32% for autumn cocoon yield per 10,000 larvae. This result indicates that there are large differences and diversity in traits among the tested mulberry germplasm resources, which can provide abundant parental materials for mulberry breeding. Correlation analysis among agronomic traits revealed that the correlation between spring mulberry cocoon yield per load and other traits was not significant, while the remaining 20 agronomic traits had certain correlations. The analysis results showed that the 21 agronomic traits affecting mulberry yield and quality were not isolated but mutually correlated. These agronomic traits coordinate and restrict each other to control mulberry quality and yield. 2. Genetic diversity and population structure analysis were conducted on 96 mulberry germplasm resources using ISSR molecular markers. A total of 93 clear bands were amplified by 10 pairs of ISSR primers, among which 73 bands were polymorphic, with a polymorphic band percentage of 78.49%. The number of amplified bands per primer ranged from 7 to 11, with an average of 9.3 bands per primer and an average of 7.3 polymorphic bands per primer. Genetic diversity analysis results showed that the average observed number of alleles per locus was 1.7957, the average effective number of alleles was 1.4964, Nei’s genetic diversity index was 0.2869, and Shannon’s information index was 0.4268. This indicates that the ISSR variation among the 96 test materials is large and the polymorphism is high. The UPGMA cluster analysis based on genetic coefficients was completely consistent with the population structure cluster analysis based on Bayesian mathematical model, both dividing the 96 tested mulberry landraces into two groups. 3. Using the mixed linear model (MLM) in TASSEL 2.1 software, with the population structure data (Q-value) calculated by Structure software as covariates, association analysis between markers and traits was conducted on 93 polymorphic marker loci, combined with phenotypic data of agronomic traits such as leaf length, leaf width and internode distance from the 96 test materials. The analysis results showed that among the 93 polymorphic loci from the 10 tested ISSR markers, 28 marker loci were significantly correlated with 15 agronomic traits including leaf length and internode distance at the extremely significant level of P<0.01, with the phenotypic variation explained rate ranging from 5.42% to 16.35%. Specifically, 2 loci were correlated with leaf length; 3 loci were correlated with internode distance, shoot germination rate and autumn cocoon yield per 10,000 larvae respectively; 5 loci were correlated with spring per-meter branch leaf yield, spring cocoon yield per 10,000 larvae and spring mulberry cocoon yield per load respectively; 2 loci were correlated with autumn per-meter branch leaf yield; 4 loci were correlated with spring leaf weight per unit, branch-stem leaf ratio and per-plant leaf yield respectively; only 1 locus was correlated with autumn leaf weight per unit; 6 loci were correlated with leaf-stem ratio; 7 loci were correlated with shoot-stem ratio and spring cocoon shell weight respectively. Among the 28 marker loci, 1 locus was simultaneously correlated with 5 agronomic traits, 4 loci were simultaneously correlated with 4 agronomic traits, 4 loci were simultaneously correlated with 3 agronomic traits, and 10 loci were simultaneously correlated with 2 agronomic traits. No marker loci correlated with 6 agronomic traits including leaf width and germination rate were detected. The research results have certain guiding significance for the exploration and utilization of genes for important agronomic traits in mulberry germplasm resources, as well as for genetic breeding.
